.alpha.-Amylase is one of the known enzymes which hydrolyzes .alpha.-1,4-linkage of starch producing a mixture of oligosaccharides. In recent years, evidence has mounted in support of the unusual action of amylases which exhibit transferring as well as hydrolyzing activity. New amylases have also been discovered from various microorganisms including maltose forming-, pullulan and/or cyclodextrin hydrolyzing-, and glucose-transferring amylases. .alpha.-Amylases from Thermoactinomyces vulgaris R-47 (Shimizu et al., Agric. Biol. Chem., 42, 1681 (1978); Sakano et al., Agric. Biol. Chem. 46, 1121 (1982) (I)) and Bacillus stearothermophilis KP 1064 (Suzuki et al., Appl. Microbiol. Biotechnol., 21, 20 (1985) (I) degrade soluble starch, yielding maltose and glucose as major products. They also hydrolyze cyclodextrins. These unusual enzymes convert pullulan to panose. A new type of pullulanase which produces panose from pullulan was also found in Bacillis stearothermophilis (Kuriki et al., J. Bacterial., 170, 1554 (1988) (I); Imanaka et al., J. Bacteriol. 171, 369 (1989)), and a gene for the enzyme was cloned and expressed in Bacillis subtilis. Suzuki et al. (Starch 39, 211 (II) isolated extracellular .alpha.-amylase II from Bacillus thermoamyloliquefaciens KP1071, which split .alpha.-1,6-linkages in amylopectin as well. This enzyme hydrolyzed .alpha.- and .beta.-cyclodextrins, and pullulans as well. David et al. (Starch 39, 436 (1987)) cloned a gene encoding the amylolytic enzyme of Bacillus megaterium. Based on the action pattern of the enzyme, it has been proposed that this enzyme hydrolyzed pullulan as well as starch. Interestingly, it also exhibited glucose transferring activity with the formation of .alpha.-1,4-linkage. With the discovery of these new amylases, the scheme of transferring activities on the starch metabolism in the microorganisms was to be elucidated and the production of maltooligosaccharides in large quantities became easier.
Applicants have cloned a gene encoding a new type of amylolytic enzyme, Bacillus licheniformis maltogenic amylase, hereinafter referred to as BLMA. The enzyme has the ability to hydrolyze pullulan and cyclodextrin as well as starch. It degrades soluble starch by cleaving maltose units preferentially. The usual thermostable amylase, BLTA, of Bacillus licheniformis produces mostly maltoheptaose from starch but cannot hydrolyze pullulan and cyclodextrins (Kim, I. C. Ph.D. thesis, Seoul National University Press, Seoul, Korea (1991)). The BLMA of the present invention also showed the catalytic properties of a new type of .alpha.-amylase which exhibited transferring activity with the formation of .alpha.-1,6-linkage, which is useful in production of branched oligosaccharide.
Finally, the Escherichia coli containing the gene encoding the novel amylolytic enzyme of the present invention was deposited at the ATCC (American Type Culture Collection, 12301 Parklawn Drive, Rockville, Md. 20852, USA) on May 7, 1990 and received ATCC Number 68319.